Pressure sensing device testing means

ABSTRACT

A pressure sensing device has a casing which communicates through a restricted orifice with a pressurized fluid line. A testing gauge is either fixed or removably connected to the casing and a variable flow valve communicates the casing with the atmosphere. The flow rate through the valve is substantially greater than the flow into the casing through the restricted orifice, thus permitting control of the pressure in the casing. Thus the pressure sensing device may be tested without removing it from the fluid line and without materially affecting the fluid pressure in the line.

United States Patent m1 Brian 3,713,325 Jan. 30, 1973 PRESSURE SENSINGDEVICE TESTING MEANS [76] Inventor: Joseph M. Brian, 428 Carlyle Avenue,Montreal, Quebec, Canada [22] Filed: Aug. 20, 1971 [21] Appl. No.:173,545

30 Foreign Application Priority Data June 3, 1971 Canada ..1 14761 [52]US. Cl. ..73/4 R [51] Int. Cl. ..GOIl 27/00 [58] Field of Search ..73/4R, 168

[56] Reterences Cited UNITED STATES PATENTS 3,398,570 8/1968 Cowan et a1..73/4

Primary Examiner-S. Clement Swisher Attorney-Fetherstonhaug'h et al.

57 ABSTRACT A pressure sensing device has a casing which communicatesthrough a restricted orifice with a pressurized fluid line. A testinggauge is either fixed or removably connected to the casing and avariable flow valve communicates the casing with the atmosphere. Theflow rate through the valve is substantially greater than the flow intothe casing through the restricted orifice, thus permitting control ofthe pressure in the casing. Thus the pressure sensing device may betested without removing it from the fluid line and without materiallyaffecting the fluid pressure in the line.

3 Claims, 2 Drawing Figures PATENTEU JAN 30 I975 INVENTOR Joseph M.BRIAN PRESSURE SENSING DEVICE TESTING MEANS This invention relates tonew and useful improvements in apparatus for testing pressure sensingdevices such asswitches, transducers and the like which are embodied inpneumatic or hydraulic systems for automatically detecting pressurechanges in pressurized fluid systems.

It is often necessary to check or change the pressure setting of such apressure sensing device, and to do this it is necessary to either removethe device from the system or to alter the pressure in the fluid line.In the instance of large pressure vessels or pressurized telephone orother communication cables or conduits it is a tedious and an expensiveprocedure to significantly raise or lower the line pressure so that acheck or a setting adjustment of the pressure sensing device can bemade.

It is, therefore the principal object of the invention to provide anarrangement whereby a pressure sensing device embodied in a pneumatic orhydraulic system.

may be quickly and easily tested and/or its pressure setting adjustedwithout the necessity of removing the same from the system and alsowithout materially affecting the fluid pressure in the line with whichthe device is associated.

The invention is particularly useful for testing pressure sensingdevices which are permanently installed at spaced points along telephonelines or cables. Such lines or cables are usually pressurized in orderto keep out moisture and the permanently installed devices automaticallydetect changes in pressure and thus possible leaks. However, the use ofthe invention is not restricted to this particular environment and theinvention may be employed in pneumatic or hydraulic systems in general,where a pressure sensing device is associated with a line carryingpressurized fluid flow or static fluid pressure. I

' With the foregoing more important object and features in view and suchother objects and features which may become apparent as thisspecification proceeds, the invention will be understood from thefollowing description taken in conjunction with the accompanyingdrawings, where like characters or reference designate like parts, andwherein:

FIG. 1 is a partly diagrammatic sectional view showing one embodiment ofthe invention; and

FIG. 2 is a fragmentary view of a slightly modified embodiment.

Referring now the accompanying drawings in detail,

and more particularly to FIG. 1, the reference character designates aline such as a cable, conduit, pipe, or the like, carrying fluid underpressure, either as a pressurized flow or, as in the instance oftelephone lines or cables, under static pressure.

A pressure sensing device 12, such as for example a pressure switch or apressure transducer, or the like, is provided at one or more pointsalong the length of the line 10, the device 12 being used toautomatically detect fluid pressure changes and possible leaks in theline, as is customary in the art. For general illustrative purposes thesensing device 12 is shown as being contained in a casing 13, theinterior of which communicates with the interior of the line 10 througha suitable connection 14 so that the device 12 is subjected to fluidpressure existing in the line.

It is desirable to occasionally test the sensing device 12 for accuracyof its setting or to adjust it from one setting to another. Inconventional practice it was necessary to remove the device from thesystem for this purpose, or, if it remained in place, to raise and lowerthe fluid pressure in the line 10 significantly so that a check or asetting adjustment of the device could be made. Particularly in theinstance of telephone cable, such a procedure was very tedious andexpensive, but with the present invention the sensing device may bequickly and easily set or adjusted or tested, without the necessity ofremoving it from the system and also without materially affecting theline pressure.

In accordance with the invention a restricted flow orifice 15 isprovided between the line 10 and the casing 13 of the device 12, as forexample in the connection 14. The casing 13 is provided with a fluidoutlet 16 communicating with the atmosphere or some other pressurereference, and a variable flow valve 17 is provided in the outlet 16.Additionally the casing 13 has an attachment point 18 to accommodate afixed or removable pressure testing gauge 19. When the gauge is removed,the opening 18 is closed by a suitable plug or check valve (not shown),and under normal operating conditions of the system the valve 17 isclosed.

However, when the sensing device 12 is to be tested or its pressuresetting is to be changed, the test gauge 19 is used to indicate thefluid pressure in the casing. The valve 17 is then opened to a greateror lesser extent, thus permitting fluid to flow from the casing 13through the outlet 16 to the atmosphere, with a resultant variation offluid pressure in the casing.

Characteristically, the size of the restricted orifice 15 is such thatthe flow capacity of the outlet valve 17 is substantially greater thanthe flow rate through the restricted orifice l5 and thus it is possibleto quickly drop the pressure in the casing 13 without materiallyaffecting the pressure existing in the line 10. By adjusting the valve17 the pressure in the casing 13 may be controlled to any desired valuefor checking the setting or performance of the sensing device 12 inrelation to the testing gauge 19.

Typically, the flow capacity of the outlet valve 17 may be from 2 to 4times greater than the flow rate through the orifice 15 for a givenpressure drop. As determined by prerequisites of the system, the orifice15 may be of a fixed size as in FIG. 1. However, under some conditionsor in some systems it may be desirable to pre-adjust the size of therestricted orifice, which may be done as exemplified in FIG. 2 whereinthe orifice or passage 15a is adjustable as to flow rate by anadjustment screw 20. Of course, once the size of the orifice 15a ispre-adjusted, its setting need not be disturbed while the outlet valve17 is manipulated during the testing procedure.

It may be emphasized that the structure shown in the drawings is forillustrative purposes only and that in actual practice the arrangementmay be quite different while still embodying the principles of theinvention. Thus for example, the outlet valve 17 and the test gauge 19may be applied to the sensing device casing 13 by means of one, commonadapter fitting. Also, the connection of the sensing device casing tothe line 10 may embody the restrictive orifice 15 as a part of theinitial installation of the permanent sensing device.

Accordingly, while in the foregoing there has been described and shownan embodiment of the invention, various modifications and equivalentsmay be resorted to within the spirit and scope of the invention asclaimed.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows.

1. In a pressurized fluid system including a fluid line and a pressuresensing device having a casing in communication with said line, andmeans for testing said pressure sensing, device without removing thesame from the system, said testing means comprising a pressure testinggauge removably connected to said casing and subjected to pressure offluid in the casing", and means for discharging fluid from thecasing tothe atmosphere at a substantially greater rate of flow than fluid entersthe casing from said line, whereby the fluid pressure in the casing maybe quickly varied without materially affecting the fluid pressure insaid line.

2. The system as defined in claim 1 which is further characterized inthat fluid enters said casing from said line through a restrictedorifice, said means for discharging fluid from the casing to theatmosphere comprising a variable flow valve having a flow capacitysubstantially greater than the flow through said restricted orifice.

3. The system a defined in claim 2 together with means for pre-adjustingthe rate of fluid flow through said restricted orifice.

1* i l l

1. In a pressurized fluid system including a fluid line and a pressuresensing device having a casing in communication with said line, andmeans for testing said pressure sensing device without removing the samefrom the system, said testing means comprising a pressure testing gaugeremovably connected to said casing and subjected to pressure of fluid inthe casing, and means for discharging fluid from the casing to theatmosphere at a substantially greater rate of flow than fluid enters thecasing from said line, whereby the fluid pressure in the casing may bequickly varied without materially affecting the fluid pressure in saidline.
 1. In a pressurized fluid system including a fluid line and apressure sensing device having a casing in communication with said line,and means for testing said pressure sensing device without removing thesame from the system, said testing means comprising a pressure testinggauge removably connected to said casing and subjected to pressure offluid in the casing, and means for discharging fluid from the casing tothe atmosphere at a substantially greater rate of flow than fluid entersthe casing from said line, whereby the fluid pressure in the casing maybe quickly varied without materially affecting the fluid pressure insaid line.
 2. The system as defined in claim 1 which is furthercharacterized in that fluid enters said casing from said line through arestricted orifice, said means for discharging fluid from the casing tothe atmosphere comprising a variable flow valve having a flow capacitysubstantially greater than the flow through said restricted orifice.